1. Field
Example embodiments may relate to apparatuses for measuring high speed signals, apparatuses capable of measuring and/or analyzing high speed signals, and/or methods thereof.
2. Description of Related Art
In general, in order to measure or analyze a high speed signal, a sample needs to be performed at a sample frequency greater than two times the maximum frequency of a signal to be measured, that is, at or above the Nyquist rate according to the well-known sampling theorem.
However, there is a case that a high speed signal having a frequency exceeding a limit of the sampling frequency of an AD converter (Analog-Digital converter) in use needs to be measured.
If the sampling frequency of the AD converter is increased, such a high speed signal may be measured according to the sampling theorem. However, the implementation of such an AD converter is limited in terms of cost and technical complication.
According to the conventional techniques, in order to measure a high speed signal without increasing the sampling frequency of an AD converter, a Parallel Sampling or Equivalent-time Sampling are employed.
The measurement of a high speed signal based on Parallel Sampling is achieved by use of a plurality of AD converters and a Data Link Layer (DLL) which provides each AD converter with a multiple phase sampling clock.
However, such a Parallel Sampling requires a great number of AD converters and a precise adjustment of a phase difference of sampling clocks.
For the Equivalent-time Sampling, if an input signal is a periodic signal, a delay is given at each sampling period of the input signal to vary the point of time at which a sampling is performed.
Such an Equivalent-time Sampling does not use a great number of AD converters, but requires a precise control of the delay.
Accordingly, there is a need for a method capable of precisely measuring high speed signals with a simple hardware architecture.